Threads of execution (“threads”) are portions of an application or an operation. An application or an operation may be split into multiple threads. Threads allow an application or an operation to be split into simultaneous or approximately simultaneous tasks. Threads may be executed in parallel. A processor switches between different threads using time slicing to give an appearance that the threads are executed simultaneously. Switching may occur quickly to give a user the appearance that threads and/or operations are being executed simultaneously. For example, multiple programs, such as media player and other applications, may be executed. The processor may switch between the programs using time slicing so that the programs may be run concurrently. Some computer systems include multiple processors which allow threads to be run simultaneously on the processors, often called multiprocessing.